1. Field of the Invention
The present invention relates to an image forming apparatus, and in particular to an image forming apparatus provided with a cooling mechanism for cooling portions which are very likely to be handled by users.
2. Description of the Related Art
In an image forming apparatus, sheet of paper is heated at the time of fixing. Subsequently the paper is cooled when it is fed and is then delivered. However, if sufficient time is not secured between the fixing and delivery, the paper is insufficiently cooled and delivered with high temperature. Particularly, in an image forming apparatus having a fixing and a delivery unit closely arranged, paper delivery temperature is a serious issue.
So, it is effective to reduce the temperature of delivered sheets of paper to provide a paper cooling mechanism in order to compensate for insufficient cooling time.
For cooling the delivered sheets of paper, for example, in a paper folding apparatus, stacking sheets of toner heat-fusing continuous printing paper having folding perforated lines on a table with the front and back side thereof being folded one after the other, detecting the front side of sheets of paper stacked on the table by means of a sensor, and lowering the table by a certain degree, it has been proposed to provide a plurality of pairs of blowers and ducts for supplying cooling air to the sheets of paper and to arrange the ducts in a longitudinal direction of the sheets of paper respectively for blowing strong and weak air from the ducts (for example, Jpn. Pat. Appln. Laid-Open Publication No. 2003-270884)
However, conventionally, when air-cooling a sheet of paper to be delivered, cooling air was blown to the entire sheet of paper, therefore, a sheet of paper may be delivered with high-temperature portions thereof not insufficiently cooled. In particular, a fixing unit becomes very hot during a fixing operation. As a result, temperature of the periphery of the fixing unit is obviously very high. For example, if image forming is repeated many times, the temperature of the photographic fixing unit reaches 160 to 170° C. If no cooling is performed, a paper delivery roller mounted on the outlet side of the fixing unit and a delivered sheet of paper reach about 100° C. If a sheet of paper is maintained at such a high temperature, there occur problems such as stripes of the paper delivery roller left on a formed image and the like. Further, the high temperature portions are not cooled immediately, and therefore, a user may come into contact with the hot portions when removing a jammed sheet of paper and the like.